1. Field of the Invention
The invention relates to a method of embedding an additional layer of error correction into an error correcting code, wherein information is encoded into code words of said code over a first Galois field and wherein a number of code words are arranged in the columns of a code block comprising a user data sub-block and a parity data sub-block. The invention relates further to a method of decoding such an error correcting code, to corresponding apparatuses, to a storage medium storing code words of such a code, to a signal comprising such code words and to a computer program for implementing said methods.
2. Description of the Related Art
A method for encoding multiword information by wordwise interleaving is disclosed in International Patent Application No. WO 00/07300, corresponding to U.S. Pat. No. 6,367,049. Therein, a so-called picket code is described consisting of two types of code words, LDC (Long Distance Code) code words and BIS (Burst Indicator Subcode) code words, which is intended to be used for DVR (Digital Video Recording) for a storing data, particularly video data, on optical record carriers. The BIS code words provide large error correcting capabilities. Even under worst case circumstances, it is extremely unlikely that they cannot be decoded correctly. After the decoding of the BIS columns, bursts of errors can be recognized. After also applying an erasure strategy, the LDC code words, which have less error correcting capabilities, can be decoded correctly.
Compared to existing error correcting codes, e.g., the product code in DVD, the picket code improves the capability of correcting (multiple) burst errors. However, the picket code is less capable of correcting random errors.